Power-operated propelling ram for railway or tramway systems



Jan. 14, 1930. A. G. KERSHAW POWER OPERATED PROPELLING RAM FOR RAILWAY OR TRAMWAY SYSTEMS Filed June 30, 1926 INVENTQR Z Patented Jan. 14, 1930 UNITED STATES PATENT OFFICE ARTHUR G. KERSHAW, OF KINGS CROSS, LONDON, ENGLAND, ASSIGNOR, BY MESNE AS- SIGNMENTS, TO THE UNION SWITCH & SIGNAL COMIANY, 0F SWISSVALE, PENN- SYLVAN IA, A CORPORATION OF PENNSYLVANIA.

POWER-OPERATED PROPELLING RAM FOR RAILWAY OR TRAMWAY SYSTEMS Application filed June 30, 1926, Serial No. 119,779, and in Great Britain September 18, 1925.

My invention relates to power operated rams for the propulsion of mining or other vehicles as employed, for instance, in connection with colliery decking plant-and has for its object to provide improved arrangements for automaticalcontrolling the action of apparatus of this character adapted to be operated by fluid under pressure.

The forward stroke of the ram may in accordance with the usual practice be arranged to be efiected by the supply of fluid under pressure controlled by an electro-magnetically operated valve device, and, according to the principal feature of the invention the reverse or return stroke of the ram is arranged to be controlled by means of avalve device which is automatically actuated by the movement of the ram plunger.

In order that the nature of the invention may be clearly understood it will now be described by way of example with reference to the accompanying drawing, the single figure of which is a diagrammatic view of a preferred constructional form of apparatus embodying the invention.

Referring now to the drawing it will be seen that the head 1 of a ram plunger 2 adapted to reciprocate in a cylinder 3 is provided with a pin or roller 4; arranged to engage during the stroke ofthe plunger 2 with two forked escapement levers 5 and 5 of which 5 is arranged adjacent to the head 1 when the plunger 2 is in its retracted position. Lever 5 is adapted to take three positions. In the first or normal position it is engaged by the pin or roller 4 as shown in the drawirg shortly after plunger 2 has commenced its outward stroke. This engagement serves to set lever 5 into a middle position.

Lever 5 is arranged towards the end of the outward stroke of plunger 2 and is also capable of occupying three difierent positions or settings, the two levers 5 and 5 being coupled together by means of a suitable link rod 6 so as to be operated simultaneously in the following manner:

When plunger 2 is in its fully retracted position lever 5 is in its normal position in which it is adapted to be engaged by the pin or roller 4 on the plunger 2 during its forward movement, the lever 5 being in an idle or inoperative position as illustrated in full lines in the drawing. Soon afterplun'ger 2 commences its forward movement the engagement of the pin or roller 4 with lever 5 takes place and lever 5 is moved to its middle position, this movement being transmitted by means .of link rod 6 to lever 5 which is thus set into its middle position, in which it is adapted to be engaged by the pin or roller l when plunger 2 reaches lever 5 this occurs lever 5 is set into its reverse position, in which it is adapted to be engaged by the pin or roller 4 upon the return or reverse movement of plunger 2, whereupon lever 5 by means of link rod 6 is restored to its middle position and is finally reset to its normal position by the engagement of the pin or roller t with lever 5 during the final return of plunger 2 to its retracted position. It will thus be seen that the beginning of the outward movement of ram plunger 2 rocks lever 5 through a predetermined arc of rotation, lever 5 then remaining stationary until plunger 2 has nearly completed its outward stroke, whereupon lever 5 is rocked through a further arc of rotation. During the return movement of plunger 2 corresponding movements of lever 5 occur in the reverse order, lever 5 being restored to its normal position in two stages.

Levers 5 and 5 are connected by means of a suitable shaft 7 to a rocking cam mechanism 8 adapted to actuate a valve device 9 comprising two valves, one 10 for controlling the supply of fluid under pressure to the cylinder 3 to eflect the reverse or return movement of plunger'2, and the other 11 for controlling the release of fluid under pressure from the cylinder 3.

The cam mechanism 8 comprises a member 8 keyed to the shaft 7, and a member 8 journalcd on the shaft 7. A portion of the member 8 extends over the curved edge of the member 8, and is adapted to be engaged by one or theother of the edges 8 or 8 of the member 8" when the shaft 7 is rotated through a sufficient angle. During the first stage of movement of the levers 5 and 5 which occurs shortly after the beginning of the out- When ward stroke of the plunger 2, the shaft 7 1s rotated in counter-clockwise direction, so that the edge 8 of the member 8 is moved toward member 8", but the angle through which shaft 7 is rotated during this first stage of movement is not large enough to cause the edge 8 of the member 8 to engage the member 8. The member 8 therefore remains in the position shown and the first stage of movement of levers 5 and 5 does in counter-clockwise direction. The roller on return of plunger 2.

the end of the rod attached to plunger 37 is then moved out of the notch in the member 8 thereby causing the valve 11 of the control valve device 9 to. close and cut off communication between the cylinder 3 and the exhaust conduit 13, communication being established, past valve 10 andthrough conduit 12, between a source of fluid under pressure, connected with a conduit 14, and cylinder 3 so as to cause the automatic During the return stroke of plunger 2 the first stage of the return movement of levers 5 and 5 does not affect the valve device 9, because the angle through which the shaft 7 is rotated in clockwise direction is not large enough to move the edge 8 of the member 8 into engagement with the member 8", and the member 8 remains in the positionto which it was last moved, thereby holding valve 11 closed and valve 10 open. Fluid under pressure therefore continues to be supplied to the cylinder 3 until the plunger 2 has nearly reached its fully retracted position, whereupon the second stage of the return movement of levers 5 and 5 rotates the shaft 7 still farther in clockwise direction, and causes the edge 8 of the member 8" to engage the member 8 and rotate the member 8 to the position in which it is illustrated in the drawing. The

- roller on the end of the rod attached to plung er'37then falls in line with the notch in the member 8, and the spring 38 returns the valve device 9 to its release position.

The shaft 7 actuated by the lev'ers 5 and 5 is arranged to operate two sets of electric contacts 15, 16, of which the contacts 15 are made when levers 5 and 5 are in their normal positions and broken when levers 5 and 5 are in their middle and reverse, positions. The contacts 16 are made when the levers 5 and 5 are in their normal and middle positions and broken when levers 5 and 5 are 1n their reverse positions.

Contact 15 is included in a circuit leading from the negative terminal X of a source of supply of operating current not shown in the drawing, through a control switch 17 and relay winding 18 to the positive terminal B of the source. Relay 18 is provided with two contact arms 1.9, 20, which move together and are actuated by relay 18. Contact 16 is included in a circuit leading from the negative terminal X of the source through an emergency switch 21 and contact arm 19 to the positive terminal B of the source of supply through energizing winding 22 of an electro-magnetically operated valve device 23 comprising two valves, one-2 1 for controlling the supply of fluid under pressure to cylinder 3 through a conduit 26 from a source of supply connected to a conduit 27 to effect the forward movement of the plunger 2, and the other 25 for controlling the release of fluid pressure from the cylinder 3 through conduit 26 and an exhaust conduit 28. A branch circuit is also established from the positive terminal B of the source 7 through the relay winding 18 and the contact arm 20 to conductor 29 leading to the emergency switch 21.

The operation of the apparatus is as follows:

The control switch 17 is first closed so that a circuit is completed from the positive terminal B of the source through the relay winding 18, the control switch 17 and the contacts 15 to the negative terminal X of the source. The relay winding 18 being thus energized a branch circuit is completed from the positive terminal B of the source through the relay winding 18, contact arm 20, emergency switch 21, and contact 16, to the negative terminal X of the source, this circuit serving to maintain the energization o f'th'e relay winding 18 when the control switch 17 is released by the operator and thus allowed to open. I V

The energization of the relay .winding18 closes contact 19 and causes a circuit to be completed from the positive terminal B of the source through the energizing winding 22 of the electro-magnetically operated valve device 23, contact arm 19, emergency switch 21, and contact 16 to the negative terminal X of the source, with the result that fluid under .pressure is supplied through conduit 27, past valve 24, and through conduit 26 to cylinder 3 to effect the forward movement of plunger 2. Soon after the forward stroke of the plunger 2 begins, levers 5 and 5 are actuated as above explained, with the result that the circuit through the control switch 17 is broken at contacts 15. As soon as plunger 2 has nearly completed its stroke, the levers '5 and 5 are moved from their middle to their reverse positions, therebyactuating the control valve device 9 as above described, and permitting fluid under pressure to be supplied from a source of supply through conduit 14 past valve 10 and through conduit 12 to cylinder 3 to effect the return movement of plunger 2. At the same time contacts 16 actuated by the levers 5 and 5 are broken, thereby de-energizing the winding 22 of the electro-magnetically actuated valve device 23 and causing the valve 24 to close and cut oil the supply of fluid under pressure'effecting the forward movement of the plunger 2. The interruption of this circuit also de-energizes the relay winding 18 so that its contact arms 19, 20 move to their open position and when the return stroke of plunger 2 is nearly completed the control valve device 9 is actuated by the cam mechanism 8 as above explained to close valve 10 and to cut oil communication between the source of supply of fluid unde pressure and the cylinder 3.

It will thus be seen that when once the operator has closed the control switch 17 the whole of the forward and return strokes of plunger 2 take place automatically.

In order to enable the plunger 2 to be arrested at any desired stage in its forward movement and to be returned to its fully retracted position, the emergency switch 21 is provided and is combined with an emergency control valve device 30' which is actuated when the emergency switch 21 is open. The emergency valve device '30 comprises two valves, one 31 for controlling the supply of fluid under pressure through a conduit 33 from a source of supply connected to a conduit 34, the other 32 for controlling the release of fluid under pressure from conduit 33 through a conduit 35. The opening of the emergency switch 21 as will. be understood from the foregoing description of the circuits involved, causes the relay winding 18 to be de-energized and thus the interruption of the supply of fluid under pressure to the cylinder 3 for its forward stroke through the electromagnetically operated valve device 23. The action of the emergency control valve device 30 is to control the supplyof fluid under pressure to a piston .36 adapted to actuate the control valve device 9 in the same manner as levers 5 and 5 that is to say, when the emergency valve device 30 is operated fluid under pressureis supplied from a source of supply through conduit 34 to piston 36, past valve 31 and through conduit 33, and causes the control valve device 9 tosupply fluid under pressure to cylinder 3 to cause the return movement of the plunger 2. The piston 36 is interposed between the valves 10 and 11, and a piston or plunger 37 actuated by cam mechanism 8, so that when the emergency valve device 30 is not operated the control valve is actuated solely by the levers 5 and 5 whereas when the emergency valve device 30 is .operated, the piston 36 operates the control valve device 5) independently of levers 5 and 5 My invention is evidently not limited to the particular mechanical and electrical arrangements above described, which may be varied to meet particular conditions without exceeding the scope of my invention.

Having now particularly described and ascertained the nature of my said invention and in what manner the same is to be performed, I declare that what I claim is:

1. Power operated ram mechanism comprising a cylinder, a plunger movable in said cylinder between two extreme positions, a contact controlled by saidplunger and arranged to be closed when and only when the plunger occupies one extreme position, a relay, manually controlled means including said contact for energizing said relay, means for subsequently holding said relay in its energized condition until the plunger moves to the second extreme position, and means controlled by said relay for at times admitting fluid pressure to said cylinder.

2. Power operated ram mechanism comprising a cylinder, a plunger movable in said cylinder between two extreme positions, a relay, manually controlled means effective when the plunger occupies one extreme position to energize said relay, means for subsequently holding said relay in its energized condition until the plunger moves to the second extreme position, a winding controlled by said relay and arranged when energized to admit fluid pressure to one end of the cylinder to move the plunger toward said second extreme position, and a valve actuated'when the plunger moves into said second position to admit fluid pressure to the opposite end of the cylinder torestore the plunger automatically to said one extreme position.

3. Power operated ram mechanism comprising a cylinder, a plunger movable in said cylinder between two extreme positions, a relay, manually controlled means effective when the plunger occupies one extreme position to energize said relay, means for subsequently holding said relay in its energized condition until the plunger moves to the second extreme position, a winding controlled by said relay and arranged when energized to admit fluid pressure to one end of the cylinder to move the plunger toward said second extreme position, two levers arranged to be engaged by said plunger at diflerent points in its stroke, and a valve controlled by said levers and arranged to admit fluid pressure to the opposite end of the cylinder when the plunger moves into said second extreme position to restore the plunger automatically to said one extreme position. 7

4. Power operated ram mechanism comprising a cylinder, a plunger movable in said cylinder between a first and a second extreme positi0n,-two levers arranged to be engaged by said plunger at different points in its stroke, a circuit controller controlled by said levers, a manually operable switch, a relay, a pick-up circuit for said relay including said 5 manually operable switch and a contact of said circuit controller, an emergency switch, a winding controlled by said emergency switch, a contact of said relay, and a contact of said circuit controllerand arranged when energized to admit fluid pressure to one end of the cylinder to move the plunger toward said second extreme position; a cam mechanism operated by said levers, a valve mechanism controlled by said cam mechanism and arranged to admit fluid pressure to the-other end of said cylinder when the plunger moves into said second extreme position to restore the plunger automatically to said first extreme position, an emergency control valve operatively' connected-With said emergency switch, and means controlled by said emergency control valve and including said valve mechanism for admitting fluid pressure to the other end of said cylinder at any time during the movement of said plunger toward said second extreme position to arrest the motion of the plunger and restore the plunger to said first extreme position.

In testimony whereof I aflix my signature. ARTHUR G. KERSHAW. 

